Gaits are defined by the relative phase between oscillators, which in the analogy of multi-legged locomotion,
may be produced by CPG or pacemaker signals which in algae we conjecture to be mediated by the basal architecture.
Flagellar apparatuses imaged by electron microscopy reveal species-specific networks of connections
which increase in complexity with flagella number [1]}.
Symmetries of an underlying network of structural couplings [2]} likely translate downstream into symmetries of
observed multiflagellate gaits (Fig. REF ).
The BB from which the flagellum nucleates is a center for conduction of morphogenetic and sensory information between
flagella and other intracellular organelles.
Although BBs are not essential for flagellar function (isolated axonemes continue to beat when reactivated in
ATP [3]}, [4]}), the contractility of inter-BB connections may contribute to coordination [5]}.
In CR robust NBBCs descending near the DF link BBs to the nucleus (Fig. REF B) remain intact even
after detergent lysis treatment [6]}, and can be induced by calcium to undergo significant contraction [7]}.
Similarly rhizoplasts of scaly algae including Pyramimonas and Tetraselmis can contract and relax cyclically [8]}, [9]}.
These species display frequent directional changes (mechanoshock) that may be mediated by the extraordinary
contractility of rhizoplasts [9]}, with normal coordination after abrupt gait changes rapidly reestablished.
Fibrillar structures under tension experience much distortion during active beating, as observed from misalignment of
fiber striation patterns [11]}.
Contraction during live beating is ATP-dependent in Polytomella [12]}, occurs in real-time in paralyzed
flagella and temperature sensitive mutants of Chlamydomonas [13]}, and to an extraordinary degree in
Microthamnion zoospores [14]}.
ATPase activity has also been identified in the rod cells of the human eye where a large striated root attaches to the
BB of a short (non-motile) cilium [15]}.
Attachment sites of contractile fibers also exhibit great specificity, in most species to specific microtubule triplets and disc complexes.
In P. octopus contractile fibers attach to the "weaker" side of BBs (triplets 6-9), and may function to
pull the flagellum back from each power stroke during its unique multi-breaststroke gait.
